1. Technical Field
The disclosure in generally relates to a memory device and a method for fabricating the same, and more particularly to a resistive random-access memory (ReRAM) device and a method for fabricating the same.
2. Description of the Related Art
Non-volatile memory (NVM) which is able to continually store information even when the supply of electricity is removed from the device containing the NVM cells. Recently, the most widespread used NVMs are charge trap flash (CTF) memory devices. However, as semiconductor features shrink in size and pitch, the CTF memory devices have its physical limitation of operation. In order to solve the problems, a ReRAM device is thus provided.
ReRAM devices that apply difference of resistance within the memory cells thereof to implementing the erase/program operation have advantages in terms of cell area, device density, power consumption, programming/erasing speed, three-dimensional integration, multi-value implementation, and the like over FLASH memory devices, and thus have become a most promising candidate for leading products in the future memory market.
A typical ReRAM device comprises a vertical arrangement of metal layer/memory layer/metal layer structure. As a result, the ReRAM device can achieve high-density storage by means of a crossbar array configuration. In order to improve the assembly of a substrate and the metal layer, a prior art method for fabricating a ReRAM device comprises steps as follows: A recess is firstly formed on the substrate, and a barrier layer is then formed on the bottom and the sidewalls of the recess. A metal material, such as tungsten (W) is next filled into the recess to form a lower electrode layer. A metal oxide layer serving as the memory layer is subsequently formed on a top surface of the lower electrode layer by an oxidation process or a deposition process. Thereafter, an upper electrode layer is formed on the metal oxide layer.
However, since the process for forming the metal oxide layer cannot has processing limitation to make the metal oxide layer entirely covering on the top surface of the lower electrode layer, thus the corner formed by the sidewalls of the recess and the top surface of the lower electrode layer may be likely exposed. As a result, an undesired electrical contact may be formed between the lower electrode layer and the upper electrode layer subsequently formed on the metal oxide layer through the corner, and the current leakage occurring on the corner may lead the ReRAM device failure.
Therefore, there is a need of providing an improved memory device and a method for fabricating the same to obviate the drawbacks encountered from the prior art.